Nightmares are a normal psychological phenomenon, a temporary state of hypoxia that occurs in the sleep state, caused by waking up from a dream when frightened, but the muscle exchange is still at rest. So the clinical symptoms of the mind not being able to dominate the body appear. The main causes of nightmares are the following: 1. If the usual work pressure is too high, overworked, stay up late for a long time, long-term anxiety, poor sleep quality or nightmares, etc., can cause nightmares to occur. 2. Incorrect sleep posture, such as lying down to rest limbs pressing on the heart, breathing difficulties, chest tightness and other symptoms, leading to nightmares. 3, too much dinner, rhinitis patients, sleep environment changes can cause nightmares. Usually rest on time without staying up late, relax before going to bed, do not have too much psychological pressure.